What are the symptoms of oculomotor nerve palsy due to lesions in the fascicular subarachnoid portion of the third cranial nerve?

Updated: Oct 08, 2018
  • Author: James Goodwin, MD; Chief Editor: Andrew G Lee, MD  more...
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The fascicles of the third cranial nerve exit the mid brain through the medial aspect of the cerebral peduncles and are not near any of the other cranial nerves at this point.

The findings of third cranial nerve palsy tend to occur in isolation from lesions in this location. The pupil fibers are superficially located within the third cranial nerve in this location; therefore, pupil involvement is a common presentation of subarachnoid space compression of the nerve (eg, aneurysm).

Since the most common lesion to affect the third cranial nerve in the subarachnoid space is aneurysm, the signs and symptoms of subarachnoid hemorrhage, including sudden severe headache, stiff neck, and loss of consciousness, may be present.

Infundibulum refers to widening of the proximal segment of the posterior communicating and other arteries, and, unlike aneurysm in this location, it is usually asymptomatic. A case of posterior communicating artery infundibulum has been reported to cause recurrent ipsilateral third cranial nerve palsy and headache that masqueraded as ophthalmoplegic migraine. [3]

Ophthalmoplegic migraine presents in childhood with recurring bouts of unilateral headache and ipsilateral third cranial nerve palsy that can last several weeks at a time. The link to migraine in general has come under question because many or most of these patients demonstrate thickening and enhancement of the cisternal portion of the third cranial nerve on MRI with gadolinium. [4]

Basal meningeal infection, neoplastic infiltration, and miscellaneous inflammatory lesions may involve the third and all the other cranial nerves. The primary symptoms of meningitis are often present, including headache, stiff neck, fever, and alteration of consciousness. Eventually, these diseases tend to involve other cranial nerves, which is not the case with a very localized lesion, such as berry aneurysm.

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